The third school and workshop in the framework of the Marie-Curie Research Training Network JETSET is organised by the Turin node, in January 2007. The main topic of the school is "Numerical MHD and Instabilities", with a special session dedicated to Visualization techniques and virtual reality.

The first JETSET school (Villard-de-Lans, France, January 2006) was dedicated to jet theories and models whereas the second school had as topic the jet observations (Marciana Marina, Elba, Italy, September 2006). High angular resolution observations have started giving us informations about the region close to the YSOs. A great challenge is posed to the numerical models in reproducing the observations by using high resolution simulations. The comparison between observational data and simulation results will test the theories and give us a better understanding of the jet propagation and acceleration mechanisms.

This school will provide an inside view on the field of numerical methods, departing from very basic aspects. These will be of interest for the participants which do not work within the field. The school will be an overview on the numerical treatment of the MHD equations, i.e. the methods used, the physics taken into account, and the approximations introduced by the numerical models. There will be discussed the non-ideal effects, now available in a number of numerical codes due to more sophisticated algorithms and increased computer power availability.

Moreover, the school intends to be an overview of the capabilities and the robustness of the "competing" algorithms of the numerical codes deviced for astrophysical problems, to inform the users about their possibilities and limitations. This in the spirit of all JETSET schools, that is to facilitate the information exchange between observers, theoreticians and simulation software developers.